1. Field of the Invention!
This invention relates to an ultrasonic vibration soldering apparatus for dipping a workpiece in solder by applying ultrasonic vibration to a solder solution heated and molten in a solder tank.
2. Description of the Prior Art!
There is known ultrasonic soldering that a workpiece is dipped in solder by applying ultrasonic vibration to solder heated and molten in a solder tank without coating a portion to be soldered of the workpiece with a flux.
In such ultrasonic soldering, an attempt is being made to apply ultrasonic vibration to the workpiece from an ultrasonic horn through the solder optimally by attaching the ultrasonic horn, a part for applying ultrasonic vibration to the solder, to the solder tank at a position below the surface of the solder in such a manner that it penetrates the wall of the solder tank and arranging the ultrasonic horn and the workpiece dipped in the molten solder to face each other. As the soldered area of the workpiece facing the ultrasonic horn expands, the ultrasonic vibration application area of the ultrasonic horn increases. Therefore, the vibration amplitude in the ultrasonic vibration application area becomes weaker and weaker as the distance of the transducer attached to the ultrasonic horn from the area increases and the solder is liable to be adhered to the workpiece to a nonuniform thickness.
As shown in FIG. 17, it has been known that the vibration amplitude state is improved by forming slots 1-10b, 1-10c, 1-10d and 1-10d in the horn main body 1-10a of an ultrasonic horn 1-10 used for bonding other than soldering and other processing making use of ultrasonic vibration. FIG. 17a is a plan view of the ultrasonic horn 1-10 which has a threaded hole 1-10f for connecting an unshown transducer or booster in the center of one end surface of the horn main body 1-10a and a plurality of slots 1-10b at an equal distance from the threaded hole 1-10f and on both right and left sides of the threaded hole 1-10f. FIGS. 17b to 17d are sectional views of variations of the slots, wherein FIG. 17b shows that a slot 1-10c is provided through the horn main body 1-10a, FIG. 17c shows that slots 1-10d are counter bored from the front and rear sides of the horn main body 1-10a and closed at an intermediate portion corresponding to the threaded hole 1-10f, and FIG. 17d shows that a slot 1-10e is counter bored from the rear side of the horn main body 1-10a and closed at the front side of the horn main body 1-10a.
When the ultrasonic horn 1-10 having the above common slots 1-10b, 1-10c, 1-10d or 1-10e shown in FIG. 17 is attached to the solder tank at a position below the surface of the solder in such a manner that it penetrates the wall of the solder tank, the solder molten inside the solder tank flows out to the outside through the slots 1-10b, 1-10c, 1-10d or 1-10e because the slots 1-10b, 1-10c, 1-10d or 1-10e communicate with both the inside and outside of the solder tank. Therefore, this constitution can be hardly employed.